After the massacre of the Northern army at the Red Wedding and the death of Robb Stark, the Blackfish reassembles the remnants of the Tully host and retakesRiverrun from House Frey, becoming the de facto leader and lord of House Tully during his nephew's captivity. Refusing to surrender his family home to the Freys, he is killed in a final stand when Jaime Lannister retakes the castle.

Brynden often argued with his older brother Hoster, particularly over the fact that Brynden never married. When Brynden returned home from the War of the Ninepenny Kings, Hoster had already arranged for him to marry Bethany Redwyne, of the wealthy and powerful House Redwyne. Brynden refused this generous match, however, refusing to be told when and whom to marry. Hoster was angry that Brynden would not do his duty to their family and enter into a marriage-alliance to improve their fortunes, and said that he was the black goat of the Tully herd. Brynden joked that given that the Tully sigil is a trout, it would be more fitting to say that he was the "black fish" of the Tully school. The nickname stuck, and Ser Brynden became popularly known as "The Blackfish" ever since. Brynden even took to using a black fish in his own personal heraldry, which like the standard Tully heraldry it uses a red and blue background, but swaps out the normal silver trout for a black one. Hoster would attempt to contract other arranged marriage-alliances for Brynden over the years, many of them very promising matches, but Brynden turned down them all, which led to constant bickering between the two brothers throughout their lives.

Despite his disagreements with his brother over his refusal to marry, Brynden is very devoted to his family.

Brynden comforts Catelyn over the death of her father and the disappearances of her two younger sons.

During the funeral of Hoster Tully, an annoyed Brynden takes the place of his nephew, Lord Edmure, after the latter fails several times to hit the funeral boat with flaming arrows. Later on he also chides Edmure for calling Robb "nephew" instead of treating him as his King as Edmure defends his course of action that led to the Battle of Stone Mill. He also consoles Catelyn when she muses about her father's funeral and whether she will ever see Bran and Rickon again, whose whereabouts are unknown following the Sack of Winterfell.[1]

The Blackfish brings Rickard Karstark and his men before King Robb after they brutally murder Willem and Martyn Lannister as revenge against House Lannister. Brynden is highly offended when Rickard makes a derogatory comment about Ned Stark and punches him in the face in retaliation. Brynden counsels King Robb not to execute Lord Karstark but instead to keep him as a hostage, thus keeping the Karstark forces loyal to the Starks. King Robb disagrees, however, and executes Lord Karstark under charges of treason while Brynden watches on along with Edmure, Talisa and Catelyn.[2]

Brynden advises his nephew to marry Walder Frey's daughter.

The Blackfish is again present when "Black Walder" and Lothar Frey come to Riverrun to discuss an alliance between House Stark and House Frey. The Freys demand that Edmure must marry one of Lord Walder Frey's daughters if the alliance is to go ahead. Edmure is reluctant to agree to these terms but Brynden tells him that he must if they have any hope of winning the war. Edmure finally relents.[3]

En route to the Twins for Edmure's wedding, Brynden agrees with Catelyn that Walder Frey is the prickliest man he has ever met, and quips that he has seen "wet shits I like more than Walder Frey".[4]

Brynden talks with Catelyn during Edmure's wedding.

When they finally reach the Twins, Brynden is visibly angered when Walder Frey lightly insults Talisa, but stays himself. During the wedding feast, he drinks heavily and brings up Roose Bolton's marriage to Frey's granddaughter Walda to further cement their alliance. Roose confides to Brynden and Catelyn that he actually did it since Frey promised him a dowry of silver matching Walda's weight. Brynden briefly goes outside to relieve himself on a tree, narrowly escaping the Red Wedding massacre that follows shortly after and claims the lives of Robb, Catelyn, Talisa and all of their Northern allies; the Blackfish either sneaked away or fought his way through the chaos to escape the Twins.[5]

Roose Bolton and Walder Frey later discover that Brynden escaped. Though Frey is undisturbed, Roose is visibly concerned that Brynden will reach the safety of Riverrun before he is found.[6]

Petyr Baelish informs Sansa Stark that Brynden has reunited the remnants of the Tully army and successfully taken back Riverrun from House Frey, and he advises her to seek her uncle out for help retaking the North. Heeding this advice, Sansa sends Brienne of Tarth to meet with Brynden.[7]

Lord Walder Frey berates his sons for losing Riverrun, and requests help from the Lannisters in taking it back, thus beginning the Second Siege of Riverrun.[8] While parleying with Jaime Lannister, the Blackfish informs him that Riverrun can hold out for two years, and that he must be ready to lose thousands of men if he wants to storm Riverrun. Realizing that the Blackfish has no intention of surrendering, Jaime is furious that he had to meet him at all.[9]

The Blackfish reads Sansa Stark's letter.

Later, Brienne of Tarth arrives with Sansa Stark's letter, asking the Blackfish to send his forces North to join Sansa and Jon's army. The Blackfish refuses to give up Riverrun, even for his great-niece. Edmure is sent to retake the castle from the Tully garrison, under threat of the murder of his son. The Blackfish knows that Edmure is not coming of his own free will, and orders the men not to let him in. Though the Blackfish commands the forces at Riverrun, formal authority is vested in Edmure as the rightful head of House Tully and the Lord of Riverrun, and his men are obliged to obey Edmure, not the Blackfish. As his men allow Edmure into Riverrun, a disheartened Blackfish leaves the battlements. Edmure orders his men to surrender and that his uncle be put in chains, but the Blackfish refuses to surrender and resolves to kill as many men as he can. He leads Brienne and her squire Podrick Payne into a waterway to escape Riverrun on a boat. He stays to die fighting for his home, though he admits he'll "probably make a fool" of himself due to a lack of recent combat experience.

A Lannister soldier later reports to Jaime that the Blackfish was killed while resisting arrest, and Jaime appears to be saddened that he has helped the Freys murder another member of Catelyn's family.[10]

Brynden Tully: "You're lucky I'm not your King. I wouldn't let you wave your blunders around like a victory flag."

Edmure Tully: "My 'blunder' sent Tywin's mad dog scurrying back to Casterly Rock with his tail between his legs! I think King Robb understands we're not going to win this war if he's the only one winning any battles!"

Walder Frey: "You did lose the Blackfish after the Red Wedding. You had him right here in this hall and you let him leave. Then, when I told you to hunt him down and kill him, you couldn't find him. That's what it means to lose something. Now he's come back and taken Riverrun."

Brynden Tully was announced as appearing in Game of Thrones and was expected to debut in the second season based on comments by George R.R. Martin. He debuted in the first novel, however his introduction to the TV series was pushed back due to time constraints. He was not cast for the first and second seasons, however, a press release confirmed he would be cast in Season 3.[11] He is played by Clive Russell.[12]

In the A Song of Ice and Fire novels, the Blackfish is a canny and respected warrior. He is tall and clean-shaven, and dons a red and blue Tully cape, like his nephew Edmure. Brynden possessed the distinctive auburn hair of the Tully family in his youth, but it has now gone mostly grey. He values his family above all else, but dislikes Jon Snow, perhaps because he reminds him of Eddard Stark's infidelity to his niece Catelyn (which he voices in "A Feast for Crows").

Brynden is an experienced battlefield commander. He rose to particular distinction during the War of the Ninepenny Kings which was fought over the Stepstones, in which he fought alongside Ser Barristan Selmy. The young Jaime Lannister highly revered him and was eager to hear of his exploits in the war.

Brynden took up the nickname "the Blackfish", after he refused to marry Bethany Redwyne, which would have advanced the family's fortunes. This led to years of bitter quarrels and estrangement with his brother Hoster. After one such quarrel with his elder brother, when Lord Hoster called him the "black goat of the Tully herd", Ser Brynden pointed out that their sigil was a fish, so he took the name "Blackfish", and changed the color scheme of his personal sigil to a jumping black trout (which is normally silver in the Tully sigil).

So far, the books have never made exactly clear why Brynden has never married, i.e. if he loved a woman who did not return his attraction, or if his brother refused to allow him to marry anyone else if he wouldn't go through with the arranged marriage to Bethany Redwyne. As the younger brother of Hoster, Lord Paramount of the Riverlands, Brynden was certainly one of the more eligible bachelors in Westeros. This has led to some fan speculation that Brynden may be a homosexual, and that this in-part caused the rift with his older brother when he refused to take part in a marriage-alliance he had brokered, but so far the books have given no particular hint that this is the case. Others speculate that Brynden may have loved Minisa Whent, but after she married his older brother Hoster, he refused to ever love again. Whatever the reason why Brynden never married, it is something of an open secret among his immediate family members: at one point Catelyn comments in passing to Edmure, regarding Brynden's disagreements with her father, that they both know why he never married.

In the novels he is first encountered serving in the Vale of Arryn, where he serves his niece, the Lady Lysa, as the Knight of the Gate, who commands the Bloody Gate. Brynden has been in service to House Arryn since the end of Robert's Rebellion, as neither he nor Hoster sought reconciliation. After Catelyn asks for his assistance and Lysa refuses to send aid after the Lannisters invade the Riverlands, Brynden resigns from his post and agrees to return to the Riverlands and help in the growing struggle against the Lannisters. In the TV series, some of Brynden's activities in the Vale have been taken over by Ser Vardis Egen.

Along with Edmure, he becomes one of King Robb Stark's most trusted lieutenants, his "eyes and ears". Theon Greyjoy references the Blackfish's talent for battle and strategy.

The Blackfish is not present during the events of the Red Wedding because Robb had left him holding Riverrun as "Warden of the Southern Marches" (a new title that Robb created), overseeing the defenses of the Stark-loyal territories of the Riverlands, and protecting his Queen, Jeyne Westerling (the book's counterpart of Talisa Maegyr), who also remained at Riverrun.

According to the agreement between Tywin Lannister and Walder Frey, Riverrun is granted to Emmon Frey, Lord' Walder's second son and husband of Tywin's sister, Genna. Following the Red Wedding, Ryman Frey leads two thousand spears to take Riverrun, reinforced by Lannister troops led by Ser Daven Lannister, and the forces of some of the Riverlords that bent the knee after the Red Wedding.

Brynden anticipates the siege. He gathers all the foodstuffs and goods he can within the castle, expels all the unnecessary mouths, and prepares for a long siege.

Ryman Frey and Jaime try to parley with Brynden, but in vain. After Jaime describes Edmure how he intends to conquer Riverrun, Edmure agrees to yield. The next morning, Brynden is missing. Edmure admits that he helped his uncle escape, by raising the portcullis on the Water Gate. After dark, Brynden pulled himself beneath the spikes. Jaime, who knows well how dangerous Brynden is, sends men to search for him, but they fail to find him. Nymeria and her pack assist Brynden to get away by attacking one of the search parties.

By the point the books reached, Brynden's current whereabouts are unknown.